I probably shouldn't even say anything. But there's always the chance I could learn something.
Here is what I thought I understood about charging. This is mostly based on charging my AGM bank, but the LFP bank doesn't really seem that different in terms of charge stages?
1) The charger can supply amps. Let's say we have a 30 amp charger.
2) "Bulk" charging will occur first. Constant current and rising voltage. Since it's only a 30 amp charger (and let's say battery bank is ~200 amp hours and maybe half discharged) it will throw everything it has (current wise) at the battery bank. As a result, the battery bank's voltage will slowly rise. The charger doesn't really "have" a voltage at this point though; it's the batteries themselves that are establishing the voltage. It rises as the batteries charge (determined by the batteries, not the charger)
3) Once the battery voltage rises to what we, the owner of the charger, have set as the "absorption" voltage, then the charger will switch to constant voltage (say, 14.2 volts). At this point, because batteries can only accept so much, the current going in will gradually fall. So voltage will be 14.2, and current might start at say 20 amps, fall to 10 amps, fall to 5 amps, etc. etc.
4) Charge is terminated in varying ways, depending on what you have set. On my AGM bank, I used tail current (i.e. when at 14.2 volts the current got to X% of the bank size - in my case it was about 2 amps). You could also use a set time (say 1 or 2 hours). Maybe there are other ways.
5) When the charge is terminated, usually it goes to Float, which you set in the parameters. 13.5volts seems to be typical, especially if you may be using the bank, and don't want to just take power back down (say if you are using solar, you want the solar to keep the battery bank at 13.5 until the sun goes down, since it can). Maybe in a situation where charging was readily available you'd set float voltage lower (13.2?).
6) Some chargers have an even "lesser" stage, called storage. I mostly charge with solar so that isn't needed since the sun goes down every night.
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So how is LFP different from my understanding above? I know there is balancing (on my bank, that starts around 13.8 volts and really gets going I think above 14 volts) but I don't think that really changes the charge stages, does it?
I wish I could understand what the scary problem was.
